Offa (ŏfˈə) [key], d. 796, king of Mercia (757–96). He succeeded Æthelbald to the throne, but it was some years before he attained the power of his predecessor. Gradually he asserted his overlordship in Kent and then Sussex, and by 774 his charters styled him rex Anglorum [king of the English]. He restricted Cynewulf, king of Wessex, to the area S of the Thames and in 794 had Ethelbert, king of the East Angles, beheaded and thereafter ruled his kingdom. In time the rulers of Wessex and Northumbria became his sons-in-law. In 786 the pope sent two legates to him, and by 788 Offa had set up an independent archbishopric of Litchfield, thus wresting control of the churches in Mercia from the hostile archbishop of Canterbury. He introduced a new coinage in the form of the silver penny, which for centuries was to be the basis of the English currency. Offa had sufficient standing in Europe to negotiate with Charlemagne as an equal; and, although they quarreled over a proposed marriage of their children, they signed (796) a commercial treaty, the first recorded in English history. At some time between 784 and 796 the earthwork known as Offa's Dyke was built between Wales and Mercia. Offa's laws, now lost, were used by King Alfred in his codification. The Offa referred to in Beowulf and other Anglo-Saxon heroic poetry was not the king of Mercia, but a king of the Angles on the Continent, probably at the end of the 4th cent.
See F. M. Stenton, Anglo-Saxon England (3d ed. 1971).
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